Conservation minister Nick Smith has thrown his weight behind calls to expand the use of 1080 to more of the conservation estate, saying he expects a report from the conservation department in a matter of weeks.

It comes after the Parliamentary Commissioner for the Environment this week called for more use of the poison used to kill pests like possums, stoats and rats.

Dr Jan Wright this week said the poison was the most effective pest control method but the current scheme was inadequate and needed to be expanded to better protect New Zealand's native fauna.

Each year around 3500 tonnes of the pellets are dumped in around one million hectares of conservation land and Smith says he is backing the calls to increase that programme.

''I am totally satisfied that 1080 is the most effective tool that we have to be able to ensure survival of many of New Zealand's iconic native species,'' he said.''The message from the commissioner is we can do more, I think she's right and that is what I'm getting the department to explore.''

While debate rages about the suitability of the poison, with opponents arguing it also kills native species, insects and deer, Smith said he no longer harboured any concerns about its safety and effectiveness.

The Department of Conservation (DOC) was responsible for more than eight million hectares of land and was currently treating about one million hectares with 1080.

''With some reconfiguration of the budget we may be able to expand that million by spending a bit less on the monitoring and reporting and that is what I've asked the department to explore,'' he said.

He would not say how much of the conservation estate the use could spread to, though has earlier said it DOC was planning an aerial drop in a further 10,000 hectares this year, but said they would focus on the areas with the highest pest density and where they believed they could encourage the greatest regeneration among native species.

Smith defended criticism of the amount DOC spent on monitoring and reporting on the use of 1080 but agreed the department was ''probably guilty of trying to hard to satisfy opponents''.

However, he rejected Wright's criticism of the amount spent on research, saying this was important.

Research into tools like automatically resetting traps was important because they were used in conjunction with aerial 1080 drops, in fringe areas, he said.

Such tools were especially useful in the island sanctuaries and greatly reduced labour costs rather than having to reset traps manually, he said.

''On the research side I remain very committed to ensuring that work continues because I think it offers long-term opportunities for big gains for conservation.''

He did not think 1080 would ever be completely replaced, however.

Smith said he expected the DOC report back ''in a matter of weeks''.

Some groups such as the 1080 National Netowrk wanted the use of 1080 completely phased out saying not enough is known about its effect on our native species and the environment. Others say it is an inhumane way to deal with pests.

United Future leader Peter Dunne has said Wright was being short-sighted and said few people believed that 1080 was an ideal solution.